You would think that a spark plug is a spark plug.... It's only purpose in life is to ignite the fuel/air mixture..... WHY what it's made of matters to these trucks is a mystery to me......

Unless you have a high energy coil, (not stock.....) stick with the factory recommended gap.

 

The rare earth materials have more resistance than copper. More resistance the more likely of a misfire if the ignition system isn't up to it. There was an episode of engine masters that ran different gaped plugs, The outcome was no difference in performance. I doubt it really has any difference in mileage either.

 

So I got the new spark plugs ordered, they arrived yesterday but I won’t be able to get them installed for a couple days as I have guests in town.

However, now after about 400 miles since last resetting the PCM, I randomly have a P0135 code come up yet again…. No idea what to do for it now seeing as I’ve verified the sensor? Perhaps exhaust leak or PCM issue? Any ideas? Or could the incorrect spark plugs somehow be potentially causing the issue?

 

Exhaust leak won't set that code..... The PCM isn't getting a signal that the heater circuit is actually powered. PCM controls the ground side of the circuit, connector 3, pin 8. Do you see power there? (engine needs to be running.....)

 

Do I see power at the PCM on connector 3 pin 8 while the engine is running? Or on the 12v power wire at the connector to the O2?

 

At the PCM. That's where it goes after the sensor. PCM controls that ground that actually activates the heater.

 

So just use one of the multimeter probes that punctures the wire? I imagine the truck won’t start with the connector #3 disconnected?

 

That would be my guess. You may be able to push something like a paperclip into the socket from the outside, to avoid poking holes in the wire.

 

Well, somehow I only have 0.45V there, and I verified continuity to the socket at the O2 sensor the other week, and know there isn't a short to ground on that, I'm guessing my PCM is awry? It's odd that I only got this engine code after several hundred miles since this was one of the prior codes and I didn't do anything other than reconnect the sensors.

 

PCM provides the ground, power comes from elsewhere. You have a problem further upstream. It might be as simply as a bad connection at the O2 sensor.